Short-Period Surface Waves from Explosions

60162 The detection and discrimination of seismic events, while monitoring for small nuclear explosions, is complicated by a significant amount of mining explosions. Complex source and propagation modeling efforts are needed to explain observational datasets of short-period surface wave generation from different types of mining and chemical explosions. This project will develop a modeling package that considers complex source models for different types of explosions and propagates explosion generated surface waves through realistic three-dimensional (3D) structures. In Phase I, a database was assembled that is unique in its content of local and regional recordings of various classifications of explosions. Source information, and in some cases videographic data from mining and chemical explosions, was obtained to help ascertain the physical processes at work during the explosions. Velocity models and attenuation values for the upper crust in the study regions were determined and will be used during the Phase II modeling study. The evidence suggests that blast discriminants can be developed from a combination of empirical and modeling efforts. Phase II will collect local and close-in data from fragmentation explosions for which a gap exists in the current database, develop a modeling package that ports different explosion source models with complicated 3D full waveform synthesis at regional distances, and compare model generated results with empirical data to develop mine blast discriminants. Commercial Applications and Other Benefits as described by the awardee: The modeling package should be useful in the synthesis of surface waves from explosions by seismological organizations. In particular, the discriminants developed would provide a tool for separating commercial mining explosions from nuclear explosions and natural seismicity. The modeling package could also have commercial applications in the mining industry to aid blasters in the design of mining explosions with high efficiency and minimal vibrational effects